From: Glauber Costa <glommer@redhat.com>
To: Jason Wang <jasowang@redhat.com>
Cc: mtosatti@redhat.com, avi@redhat.com, kvm@vger.kernel.org
Subject: Re: [PATCH kvm-unit-test 2/6] Introduce atomic operations
Date: Fri, 27 Aug 2010 08:39:30 -0300 [thread overview]
Message-ID: <20100827113930.GN2985@mothafucka.localdomain> (raw)
In-Reply-To: <20100827054920.7409.41514.stgit@FreeLancer>
On Fri, Aug 27, 2010 at 01:49:20PM +0800, Jason Wang wrote:
> +u64 atomic64_cmpxchg(atomic64_t *v, u64 old, u64 new)
> +{
> + u64 ret;
> + u64 _old = old;
> + u64 _new = new;
> +
> + asm volatile("lock cmpxchgq %1,%2"
> + : "=a" (ret)
> + : "r" (_new),
> + "m" (*(volatile long *)&v->counter), "0"(_old)
> + : "memory"
> + );
> + return ret;
> +}
> +
This is wrong.
See http://git.kernel.org/?p=linux/kernel/git/x86/linux-2.6-tip.git;a=commitdiff;h=113fc5a6e8c2288619ff7e8187a6f556b7e0d372
you need to explicitly mark you are changing the memory, here.
Btw, this is mostly header copying, and can miss bug fixes like the one above. Isn't there
a way to just specify in the test they are needed, and then grab them from linux automatically?
next prev parent reply other threads:[~2010-08-27 11:39 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-08-27 5:49 [PATCH kvm-unit-test 0/6] Kvmclock test Jason Wang
2010-08-27 5:49 ` [PATCH kvm-unit-test 1/6] Introduce memory barriers Jason Wang
2010-08-27 5:49 ` [PATCH kvm-unit-test 2/6] Introduce atomic operations Jason Wang
2010-08-27 11:39 ` Glauber Costa [this message]
2010-08-29 9:39 ` Avi Kivity
2010-08-27 5:49 ` [PATCH kvm-unit-test 3/6] Export tsc related helpers Jason Wang
2010-08-27 5:49 ` [PATCH kvm-unit-test 4/6] Introduce atol() Jason Wang
2010-08-27 5:49 ` [PATCH kvm-unit-test 5/6] Add a simple kvmclock driver Jason Wang
2010-08-27 11:31 ` Glauber Costa
2010-08-27 5:49 ` [PATCH kvm-unit-test 6/6] Add a test for kvm-clock Jason Wang
2010-08-27 11:27 ` Glauber Costa
2010-08-30 3:07 ` Jason Wang
2010-08-27 11:34 ` Glauber Costa
2010-08-30 3:27 ` Jason Wang
2010-08-28 1:58 ` Zachary Amsden
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